1. Field of the Invention
The present invention relates to a base, a full-line printhead, and a printing apparatus and, more particularly, to a full-line printhead that performs printing in accordance with, for example, an inkjet method and a printing apparatus that performs printing using the same.
2. Description of the Related Art
The element substrate of a printhead included in an inkjet printing apparatus (to be referred to as a printing apparatus hereinafter) is formed from a semiconductor integrated circuit. To implement printing at a higher speed, there has been proposed a full-line printhead in which a plurality of element substrates are arranged to obtain a print width equal to or more than the width of a print medium in advance. For example, Japanese Patent Laid-Open No. 2011-046160 discloses such a full-line printhead.
As a clock signal (CLK) used to supply an image data signal (DATA) or a latch signal (LT) to the element substrates of a full-line printhead, a signal common to the plurality of element substrates is used. Hence, from the viewpoint of the wiring space of a printed board on which the plurality of element substrates are integrated, the clock signal is supplied using one-to-many connection (multidrop connection). On the other hand, the element substrates use individual image data signals (DATA). Hence, the image data signals are supplied using one-to-one connection (point-to-point connection).
Since the image data signals are supplied by one-to-one connection, a high waveform quality is obtained in all element substrates. However, the clock signal that is supplied using one-to-many connection causes multiple reflection because the plurality of element substrates are connected. The waveform of the clock signal supplied to an element substrate far apart from the terminating resistor has a deteriorated quality as compared to the waveform of the clock signal supplied to an element substrate close to the terminating resistor. In addition, the signal amplitude becomes small. For this reason, in the element substrate arranged far apart from the terminating resistor, a signal amplitude difference between the image data signal and the clock signal occurs. When the signal amplitude is small, the rise and fall of a single-ended signal after amplification by a reception circuit that receives the signal become blunt. Hence, when an amplitude difference between the image data signal and the clock signal occurs, it results in a difference between the rise and fall of the single-ended signal after amplification by the reception circuit.
FIG. 13 is a view showing the single-ended waveforms of the image data signal (DATA) and the clock signal (CLK) after amplification by reception circuits provided in a plurality of element substrates integrated on a conventional full-line printhead.
As is apparent from FIG. 13, in an element substrate 101-1 close to a terminating resistor, the image data signal (DATA) and the clock signal (CLK) have no amplitude difference. For this reason, no difference between the rise and fall of the single-ended waveform after amplification by the reception circuit occurs. To the contrary, in an element substrate 101-4 far apart from the terminating resistor, an amplitude difference between the image data signal (DATA) and the clock signal (CLK) occurs. For this reason, it results in a difference between the rise and fall of the single-ended waveform after amplification by the reception circuit. As a consequence, the margin of Setup/Hold time of the image data signal and the clock signal becomes small, and the element substrate might be no longer able to receive a correct data signal.